fix(rest): validate storage credentials in LoadTableResult::Validate

Author: plusplusjiajia

src/iceberg/catalog/rest/types.h

@@ -187,6 +187,18 @@ struct ICEBERG_REST_EXPORT StorageCredential {
   std::string prefix;
   std::unordered_map<std::string, std::string> config;
 
+  /// \brief Validates the StorageCredential. The REST spec requires both a
+  /// prefix and config; non-empty matches Java `Credential.validate()`.
+  Status Validate() const {
+    if (prefix.empty()) {
+      return ValidationFailed("Invalid storage credential: prefix must be non-empty");
+    }
+    if (config.empty()) {
+      return ValidationFailed("Invalid storage credential: config must be non-empty");
+    }
+    return {};
+  }
+
   bool operator==(const StorageCredential& other) const = default;
 };
 
@@ -203,6 +215,9 @@ struct ICEBERG_REST_EXPORT LoadTableResult {
     if (!metadata) {
       return ValidationFailed("Invalid metadata: null");
     }
+    for (const auto& credential : storage_credentials) {
+      ICEBERG_RETURN_UNEXPECTED(credential.Validate());
+    }
     return {};
   }
 

src/iceberg/test/rest_json_serde_test.cc

@@ -2612,4 +2612,18 @@ TEST(FetchPlanningResultResponseRoundtripTest, FailedWithError) {
   EXPECT_EQ(*result, *result2);
 }
 
+TEST(StorageCredentialValidateTest, RequiresPrefixAndConfig) {
+  EXPECT_THAT(
+      (StorageCredential{.prefix = "s3", .config = {{"s3.region", "us"}}}.Validate()),
+      IsOk());
+
+  auto empty_prefix = StorageCredential{.prefix = "", .config = {{"s3.region", "us"}}};
+  EXPECT_THAT(empty_prefix.Validate(), IsError(ErrorKind::kValidationFailed));
+  EXPECT_THAT(empty_prefix.Validate(), HasErrorMessage("prefix must be non-empty"));
+
+  auto empty_config = StorageCredential{.prefix = "s3", .config = {}};
+  EXPECT_THAT(empty_config.Validate(), IsError(ErrorKind::kValidationFailed));
+  EXPECT_THAT(empty_config.Validate(), HasErrorMessage("config must be non-empty"));
+}
+
 }  // namespace iceberg::rest